* types of locks: 1) the hash table lock array, and 2) the
* arc list locks.
*
- * Buffers do not have their own mutexs, rather they rely on the
- * hash table mutexs for the bulk of their protection (i.e. most
- * fields in the arc_buf_hdr_t are protected by these mutexs).
+ * Buffers do not have their own mutexes, rather they rely on the
+ * hash table mutexes for the bulk of their protection (i.e. most
+ * fields in the arc_buf_hdr_t are protected by these mutexes).
*
* buf_hash_find() returns the appropriate mutex (held) when it
* locates the requested buffer in the hash table. It returns
int zfs_arc_grow_retry = 0;
int zfs_arc_shrink_shift = 0;
int zfs_arc_p_min_shift = 0;
+int zfs_arc_memory_throttle_disable = 1;
+int zfs_disable_dup_eviction = 0;
int zfs_arc_meta_prune = 0;
/*
kstat_named_t arcstat_l2_size;
kstat_named_t arcstat_l2_hdr_size;
kstat_named_t arcstat_memory_throttle_count;
+ kstat_named_t arcstat_duplicate_buffers;
+ kstat_named_t arcstat_duplicate_buffers_size;
+ kstat_named_t arcstat_duplicate_reads;
kstat_named_t arcstat_memory_direct_count;
kstat_named_t arcstat_memory_indirect_count;
kstat_named_t arcstat_no_grow;
{ "l2_size", KSTAT_DATA_UINT64 },
{ "l2_hdr_size", KSTAT_DATA_UINT64 },
{ "memory_throttle_count", KSTAT_DATA_UINT64 },
+ { "duplicate_buffers", KSTAT_DATA_UINT64 },
+ { "duplicate_buffers_size", KSTAT_DATA_UINT64 },
+ { "duplicate_reads", KSTAT_DATA_UINT64 },
{ "memory_direct_count", KSTAT_DATA_UINT64 },
{ "memory_indirect_count", KSTAT_DATA_UINT64 },
{ "arc_no_grow", KSTAT_DATA_UINT64 },
ASSERT(list_link_active(&ab->b_arc_node));
list_remove(list, ab);
if (GHOST_STATE(ab->b_state)) {
- ASSERT3U(ab->b_datacnt, ==, 0);
+ ASSERT0(ab->b_datacnt);
ASSERT3P(ab->b_buf, ==, NULL);
delta = ab->b_size;
}
hdr->b_buf = buf;
arc_get_data_buf(buf);
bcopy(from->b_data, buf->b_data, size);
+
+ /*
+ * This buffer already exists in the arc so create a duplicate
+ * copy for the caller. If the buffer is associated with user data
+ * then track the size and number of duplicates. These stats will be
+ * updated as duplicate buffers are created and destroyed.
+ */
+ if (hdr->b_type == ARC_BUFC_DATA) {
+ ARCSTAT_BUMP(arcstat_duplicate_buffers);
+ ARCSTAT_INCR(arcstat_duplicate_buffers_size, size);
+ }
hdr->b_datacnt += 1;
return (buf);
}
ASSERT3U(state->arcs_size, >=, size);
atomic_add_64(&state->arcs_size, -size);
buf->b_data = NULL;
+
+ /*
+ * If we're destroying a duplicate buffer make sure
+ * that the appropriate statistics are updated.
+ */
+ if (buf->b_hdr->b_datacnt > 1 &&
+ buf->b_hdr->b_type == ARC_BUFC_DATA) {
+ ARCSTAT_BUMPDOWN(arcstat_duplicate_buffers);
+ ARCSTAT_INCR(arcstat_duplicate_buffers_size, -size);
+ }
ASSERT(buf->b_hdr->b_datacnt > 0);
buf->b_hdr->b_datacnt -= 1;
}
}
/*
+ * Called from the DMU to determine if the current buffer should be
+ * evicted. In order to ensure proper locking, the eviction must be initiated
+ * from the DMU. Return true if the buffer is associated with user data and
+ * duplicate buffers still exist.
+ */
+boolean_t
+arc_buf_eviction_needed(arc_buf_t *buf)
+{
+ arc_buf_hdr_t *hdr;
+ boolean_t evict_needed = B_FALSE;
+
+ if (zfs_disable_dup_eviction)
+ return (B_FALSE);
+
+ mutex_enter(&buf->b_evict_lock);
+ hdr = buf->b_hdr;
+ if (hdr == NULL) {
+ /*
+ * We are in arc_do_user_evicts(); let that function
+ * perform the eviction.
+ */
+ ASSERT(buf->b_data == NULL);
+ mutex_exit(&buf->b_evict_lock);
+ return (B_FALSE);
+ } else if (buf->b_data == NULL) {
+ /*
+ * We have already been added to the arc eviction list;
+ * recommend eviction.
+ */
+ ASSERT3P(hdr, ==, &arc_eviction_hdr);
+ mutex_exit(&buf->b_evict_lock);
+ return (B_TRUE);
+ }
+
+ if (hdr->b_datacnt > 1 && hdr->b_type == ARC_BUFC_DATA)
+ evict_needed = B_TRUE;
+
+ mutex_exit(&buf->b_evict_lock);
+ return (evict_needed);
+}
+
+/*
* Evict buffers from list until we've removed the specified number of
* bytes. Move the removed buffers to the appropriate evict state.
* If the recycle flag is set, then attempt to "recycle" a buffer:
hash_lock = HDR_LOCK(ab);
have_lock = MUTEX_HELD(hash_lock);
if (have_lock || mutex_tryenter(hash_lock)) {
- ASSERT3U(refcount_count(&ab->b_refcnt), ==, 0);
+ ASSERT0(refcount_count(&ab->b_refcnt));
ASSERT(ab->b_datacnt > 0);
while (ab->b_buf) {
arc_buf_t *buf = ab->b_buf;
if (type == ARC_BUFC_METADATA && arc_meta_used >= arc_meta_limit)
return (1);
-#ifdef _KERNEL
- /*
- * If zio data pages are being allocated out of a separate heap segment,
- * then enforce that the size of available vmem for this area remains
- * above about 1/32nd free.
- */
- if (type == ARC_BUFC_DATA && zio_arena != NULL &&
- vmem_size(zio_arena, VMEM_FREE) <
- (vmem_size(zio_arena, VMEM_ALLOC) >> 5))
- return (1);
-#endif
-
if (arc_no_grow)
return (1);
* This is a prefetch access...
* move this block back to the MRU state.
*/
- ASSERT3U(refcount_count(&buf->b_refcnt), ==, 0);
+ ASSERT0(refcount_count(&buf->b_refcnt));
new_state = arc_mru;
}
callback_list = hdr->b_acb;
ASSERT(callback_list != NULL);
if (BP_SHOULD_BYTESWAP(zio->io_bp) && zio->io_error == 0) {
- arc_byteswap_func_t *func = BP_GET_LEVEL(zio->io_bp) > 0 ?
- byteswap_uint64_array :
- dmu_ot[BP_GET_TYPE(zio->io_bp)].ot_byteswap;
- func(buf->b_data, hdr->b_size);
+ dmu_object_byteswap_t bswap =
+ DMU_OT_BYTESWAP(BP_GET_TYPE(zio->io_bp));
+ if (BP_GET_LEVEL(zio->io_bp) > 0)
+ byteswap_uint64_array(buf->b_data, hdr->b_size);
+ else
+ dmu_ot_byteswap[bswap].ob_func(buf->b_data, hdr->b_size);
}
arc_cksum_compute(buf, B_FALSE);
abuf = buf;
for (acb = callback_list; acb; acb = acb->acb_next) {
if (acb->acb_done) {
- if (abuf == NULL)
+ if (abuf == NULL) {
+ ARCSTAT_BUMP(arcstat_duplicate_reads);
abuf = arc_buf_clone(buf);
+ }
acb->acb_buf = abuf;
abuf = NULL;
}
}
/*
- * "Read" the block block at the specified DVA (in bp) via the
+ * "Read" the block at the specified DVA (in bp) via the
* cache. If the block is found in the cache, invoke the provided
* callback immediately and return. Note that the `zio' parameter
* in the callback will be NULL in this case, since no IO was
/* this block is in the ghost cache */
ASSERT(GHOST_STATE(hdr->b_state));
ASSERT(!HDR_IO_IN_PROGRESS(hdr));
- ASSERT3U(refcount_count(&hdr->b_refcnt), ==, 0);
+ ASSERT0(refcount_count(&hdr->b_refcnt));
ASSERT(hdr->b_buf == NULL);
/* if this is a prefetch, we don't have a reference */
}
/*
+ * Notify the arc that a block was freed, and thus will never be used again.
+ */
+void
+arc_freed(spa_t *spa, const blkptr_t *bp)
+{
+ arc_buf_hdr_t *hdr;
+ kmutex_t *hash_lock;
+ uint64_t guid = spa_load_guid(spa);
+
+ hdr = buf_hash_find(guid, BP_IDENTITY(bp), BP_PHYSICAL_BIRTH(bp),
+ &hash_lock);
+ if (hdr == NULL)
+ return;
+ if (HDR_BUF_AVAILABLE(hdr)) {
+ arc_buf_t *buf = hdr->b_buf;
+ add_reference(hdr, hash_lock, FTAG);
+ hdr->b_flags &= ~ARC_BUF_AVAILABLE;
+ mutex_exit(hash_lock);
+
+ arc_release(buf, FTAG);
+ (void) arc_buf_remove_ref(buf, FTAG);
+ } else {
+ mutex_exit(hash_lock);
+ }
+
+}
+
+/*
* This is used by the DMU to let the ARC know that a buffer is
* being evicted, so the ARC should clean up. If this arc buf
* is not yet in the evicted state, it will be put there.
ASSERT3U(*size, >=, hdr->b_size);
atomic_add_64(size, -hdr->b_size);
}
+
+ /*
+ * We're releasing a duplicate user data buffer, update
+ * our statistics accordingly.
+ */
+ if (hdr->b_type == ARC_BUFC_DATA) {
+ ARCSTAT_BUMPDOWN(arcstat_duplicate_buffers);
+ ARCSTAT_INCR(arcstat_duplicate_buffers_size,
+ -hdr->b_size);
+ }
hdr->b_datacnt -= 1;
arc_cksum_verify(buf);
#ifdef _KERNEL
uint64_t available_memory;
+ if (zfs_arc_memory_throttle_disable)
+ return (0);
+
/* Easily reclaimable memory (free + inactive + arc-evictable) */
available_memory = ptob(spl_kmem_availrmem()) + arc_evictable_memory();
-#if defined(__i386)
- available_memory =
- MIN(available_memory, vmem_size(heap_arena, VMEM_FREE));
-#endif
if (available_memory <= zfs_write_limit_max) {
ARCSTAT_INCR(arcstat_memory_throttle_count, 1);
mutex_exit(&l2arc_buflist_mtx);
if (pio == NULL) {
- ASSERT3U(write_sz, ==, 0);
+ ASSERT0(write_sz);
kmem_cache_free(hdr_cache, head);
return (0);
}
module_param(zfs_arc_p_min_shift, int, 0444);
MODULE_PARM_DESC(zfs_arc_p_min_shift, "arc_c shift to calc min/max arc_p");
+module_param(zfs_disable_dup_eviction, int, 0644);
+MODULE_PARM_DESC(zfs_disable_dup_eviction, "disable duplicate buffer eviction");
+
+module_param(zfs_arc_memory_throttle_disable, int, 0644);
+MODULE_PARM_DESC(zfs_arc_memory_throttle_disable, "disable memory throttle");
+
module_param(l2arc_write_max, ulong, 0444);
MODULE_PARM_DESC(l2arc_write_max, "Max write bytes per interval");
git://git.camperquake.de / zfs.git / blobdiff